Rotary actuators



MalCh 7; 1961 G. H. LELAND ETAL v 2,973,748

ROTARY ACTUATORS Filed June 19, 1959 11E 5 GERALD H. aM/ and OL/VE/ F D4W5, 0656/650 Units@ Se@ Preis ROTARY ACTUAToRs y Filed June 19, 1959,Ser. No. 821,447 4 claims. (Cl. 121-48) This inventionrelates to arotary actuator and more particularly to a duid powered device forimparting stepwise rotary motion to an output shaft, however, the'invention is not necessarily so limited.

2. 22 and a cylindrical extension of the sleeve bearing 24. This bladder34 is preferably molded so as to have a single open seam 36 in its outerperiphery. This seam is sealed by compressing the adjacent marginalportions of the bladder between the end plate H14 and the adjacent end`of the housing member 12, the compressive force The presentapplicationk constitutes a continuation-inpart of the copenclingapplication Serial No. 726,942, led April 7, 1958, by Gerald H. Lelandand Oliver F. Davis for a Rotary Actuator. This copending applicationdiscloses a rotary actuator which is powered by fluid under y, pressureand which is characterized by a rotary output stroke which islarge inrelation to the linearuid displacement in the actuator. vThe Adevice isalso characterized by being small and compact in'view of the powertransmitted. The present invention is the resultof eiforts to improvethe means with which the propelling iluid is contained within thedevice.

An object of the present invention is to provide an improved iiuidreceiving chamber construction for a fluid powered rotary actuator.

Other objects and advantages reside in the construction of parts, thecombination thereof, the method of manufacture and the mode ofoperation, as will become more apparent from the following description.

In the drawing,

Figure l is a top plan View of the rotary actuator of this invention.

Figure 2 is a` sectional view taken substantially along the line 2-2ofFigure 1.

Figure 3 is a sectional View taken substantially Ialong the line 3--3 ofFigure 2. Y

Figure'4 is a sectional view like that of Figure 3 illus-` trating -adilferent position for the rotary actuator.y

Figure 5 is a sectional View analogous to that of Figure 2 illustratinga modification. A

Referring to the drawing in greater detail, -a rotary actuator isillustrated in Figures l andZ. This rotary actuator comprises agenerally cylindrical housing member 12 enclosed at one end by an endplate 14 'and lat the other end by a hub 16.` As best seen in Figurel,the end plate 1.4 is reenforced with radial ribs 15 so that it will havestrength to contain a fluid under pressure. Bolts 18 secure the endplate 14 to one end of the housing member .12 and boltsZti secure thehub 1 6 to the opposite end of the housing member 12.A

A shaft 22 is journalled in the end plate 14 and in the hub 16 for.rotary movement about angaxis coincident with the geometric axis of thehousing member' 12. For this purpose, sleeve bearings 24 and 26 areprovided in thee'nd plate 14 and in the hub 1 6 respectively. The` shaft22 has an intermediate spline portion 2S comprising parallel key wayswhich project outwardlyV beyond the periphery of the shaft.' Then shaftis secured against axialr movement by means'of washers 30 and. 312engaging the opposite Tendsfof the spline portion. The washer 30 bearsagainst `the sleeve bearing V24 while the washer 3,2 bears against an`inner surface of thehub 16. j

erally toroidal elastomeric bladder' 34 encircles the shaftV beingsupplied by the bolts 118. To facilitate assembly, the margins of thebladder at the seam 36 are beaded as illustrated and seated incomplementary grooves in the end plate 14 and in the end of the housingmember 12..

Provision for introduction of iluid into the bladder 34 is afforded bymeans of a passage 38 leading laterally into the end plate 14 andopening to the inner face thereof. -A tubular pin 40 penetrating theadjacent wall of the bladder 34 is press-fitted in the inner end of thepassage 3'8. Within the bladder 34, this pin 40 has an annular outwardlyprojecting ange 42 compressingthe wall of the bladder 34 against theinner face of the end plate i4 to elfect a uid seal. The outer 4endofthe passage 3S is provided with an internally threaded portion 44 forreceipt of a suitable iittng.

Adjacent the bladder 34 is' an annular thrust plate 46 f journalled forsliding axial movement on the sleeve bearing 24. interposed between thethrust plate 46 and the bladder 34 are two annular shims or plates 48and Si) Y encircling thesleeve bearing 24. The shim 48 has a centralaperture larger than the diameter of thesleeveV bearing 24 so that playexists between this shim and the sleeve bearing. The same shim snuglytits the-inner Wall of the housing member 12'. The shim 50 has an outerdiameter less than the inner diameter of the housing member 12 so thatplay exists between this shim and the housing member 12, however, thissame shim has a central aperture snugly fitting the sleeve bea-ring 24.As a resultof this construction, the shims 48 and S0 collectively make asnug tit both with the inner wall of the housing member 12 and with theperiphery of the sleeve bearing 24 while automatically compensating forany eccentricity between the housing member 12 `and the sleeve bearing24. These two shims cooperate to prevent-extrusion of the'bladder 34around the thrust plate 46 as Viiuid under pressure is introduced intothe `bladder 34 to deliver thrust'y the plate 46, coacts with a paralleland adjacent annular plate.62 through the medium of ball elements 64,there being three ball elements 64 interposed between the plates 52 and62 at 120 degree intervals.` As best seen in Figures 3 and 4, these ballelements 6,4 are caged or r trapped between opposing recesses 66 and 68in the` plates` 52 and 62 respectively. The recesses 66 and 615 areinclined oppositely from the interface between the plates 52 and 62 andfollow an arcuate path concentric with respect to the shaft 22.Referring to the position o-f the plates 52 and 62 illustrated in Figure4, it will be observed that the application of an -axial thrust to theplate 52 will induce the ball" element between the plates 52 and 62 toroll toward the deep ends of the recesses 66 and 68. To accommodate such'rolling movement,

`V`the Aplates, 52 and 62 are induced to rotate one relative to theother `about the axis of the shaft 22, such rotary motion bringing theplates 52 and 62 tothe relative position illustrated in Figure f3. It isthus apparent that an axial movement ofthe thrust plate 46 so as tocompress ftheplates 52 :and 62 will be eifective to induce rotation `ofthe plate 52 relative to the plate 62.

Patented Mar. 7, i961.

groove 6i) in the The plate 52 is secured against rotation relative tothe shaft 22 bymeans of a` hub portion 70 slidably engaging the splineportion 28 of the' shaft 22. The plate 62 is secured against rotationrelative to the housing member 12 during the time that an axialv thrustis delivered thereto by means of av clutch disc 72 interposedv betweenthe plate 62 and an adjacent shoulder 74 in the housing member 12. Thearrangement is such that the plate 62 is rotatable in the housing member12 when the bladder 34 is deflated, but is secured against rotationrelative to the housing member 12 when fluid under pressure isintroduced into the bladder 34.

Extending axially from the plate 62 is a cylindrical hub portion 76which is engaged by a coil spring 78 anchored to the spline portion 2Sof the shaft 22. This spring 78 biases the plate 62 relative to theplate 52 -to the position illustrated in Figure 4. Adjacent the spring78 an annular detent wheel S slidably engages the spline portion 28 ofthe shaft 22. Notches in the periphery of the detent wheel 80 areengaged by a ball element 82 spring biased radially inwardly by a spring84. Tension of the spring 84 is adjustable by means of a set screw 86threadedly engaging the hub 16.

The notches in the periphery of the detent wheel 80 are spaced adistance corresponding -to the rotational movement induced by therecesses 66 and 68, which is substantially twice the arcuate length ofeach of the recesses. Hence, the central angle between adjacent notchesin the detent wheel 80 is equal substantially to twice the central anglesubtended by one of the recesses 66 or 68.

The operation is as follows: With the bladder 34 deilated and with theball element 82 engaging one of the notches in the detent wheel 80, thespring 78 urges the plate 62 relative to the plate 52 so as to align theopposing recesses 66 and 68, as illustrated in Figure 4. Upon theintroduction of uid under pressure into the bladder 34, an axial forceis transmitted to the plate 62 which is restrained from rotationrelative to the housing member 12 through pressured contact with theclutch disc 72. As the axial thrust increases, the plate 52 receives arotational torque inducing it to rotate relative to the plate 62. Thistorque is transmitted to the spline portion 28 of the shaft 22 and, whenthis torque is great enough to force the ball element 82 out of itsnotch in the detent wheel 80, the plate 52 and shaft 22 rotate throughan angle determined by the recesses 66 and 68. When the plate 52 hasreached the extreme of its rotary movement relative to the plate 62, theball element 82 engages a new notch in the detent wheel 80.k Uponsubsequent reduction of the fluid pressure in the bladder 34, the plate62 becomes free to rotate relative to the housing member 12 and thespring 78 restores the plate 62 to the relative position illustrated inFigure 4. This restoring movement causes the plates 52 and 62 toseparate with the result that the bladder 34 is partially collapsed.

In View of this type of operation, it is apparent that repeatedintroduction of uid under pressure into the bladder 34 will produce astepwise rotary movement of the output shaft 22 which may be usedconstructively in any desirable manner.

Figure 5 illustrates a modified uid powered rotary actuator 100 whichembodies the present invention. This actuator is a dual unit constructedto actuate a shaft selectively in opposite directions. The housing forthe dual actuator comprises generally two cylindrical housing members102 and 104 secured to opposite sides of a central plate 106 by means ofbolts 108. A toroidal bladder 112 is secured to each side of the plate106 by compressing beaded marginal portions 110 of the bladders betweenthe housing members and the surfaces of the plate 106. Provision for theintroduction of fluid under pressure to the bladders 112 isaifordedbyinlet conduits 114 located in the plane of the plate 106 andprojecting laterally therein.

Two conduits 114 communicate with the bladder 112 to the left of theactuator, as viewed in Figure 5. One of these conduits serves as aninlet and the other serves as an outlet, suitable external valving, notshown, being employed to regulate the ow of fluid. Similar conduitscommunicating with the bladder to the right of the plate 106, as viewedin Figure 5, are located at degrees to those visible, hence are notvisible in the illustration.

Communication from the conduits 114 to the interior of the bladders 112is provided by tubular pins 116 presstted within the inner ends of theconduits 114 and penetrating to the interior of the bladders 112..Inside the t' bladders the pins 116 are provided with outwardlyprojecting annular flanges 119 which compress the adjacent margins ofthe bladders against the plate 106.

A shaft 118 normal to the central plate 106 and passing centrallytherethrough is journalled in the outer ends of the housing members 102and 104. For this purpose, sleeve bearings 120 are provided in the endsof the housing members. These sleeve bearings may be a plastic, such assintered nylon, or they may be any suitable metal having a low coeicientof friction in contact with the metal of the shaft 118. The centralportion of the shaft 118 intermediate the ends of the housing members102 and 104 is provided with outwardly projecting longitudinal key waysforming a spline 122.

A mechanism for converting axial movement induced by the bladders 112 torotary movement of the shaft 118 substantially identical to that of theembodiment of Figures l and 2 is employed on each side of this dualactuator. For convenience, like parts of this mechanism are given likereference numerals with the letter' a added to differentiate the twoembodiments. Thus, on each side of the dual actuator two opposing plates52a and 62a separated by ball elements 64a are employed. The ballelements 64a are trapped in inclined arcuate recesses and are effectiveupon the application of axial pressure to the plate 52a to inducerelative rotation between the plates. The plate 52a is secured to a hub70a splined to the shaft 118. The plate 62a is biased by a spring 78aanchored to a `spline portion of the shaft 118. The plate 62a alsocoacts with an adjacent shoulder in the housing through the medium of aclutch lining 72a.

An axial thrust is transmitted from the toroidal bladder 112 to theconversion mechanism by means of an annular thrust plate 124 encirclingthe shaft 118 land separated from the adjacent plate 52a of theconversion mechanism by means of hall elements 126 which form a thrustbearing. As with theY embodiment of Figures 1 and 2, the bladders 112are protected from extrusion around the thrust plates 124 by means ofshims 48a and 50a interposed therebetween, the shims 48a snugly fittingthe interior of the housing members and the shims 50a snugly fittingsleeve members 130 press-fitted in the plate 106 in surrounding relationto the splined portion of the shaft 118. In lieu of a caging member forthe ball elements 126, flat spring members 128 are interposed betweenthe shims 50a andthe thrust plates 124 on each side of the dualactuator. These springs preload the ball bearing 126 and also take upany play in the conversion mechanisms.

Rotary movement of the shaft 118 is regulated by a detent wheel 132splined to the shaft 118 and situated within the interior of the plate106. A plug 134 provided in the left side of the plate 106 as viewed inFigure 5, locks the detent wheel 132 in the interior of the plate 106.This detent wheel is provided with notches engaged by a suitable ballelement analogous to the ball element 82 of the embodiment of Figures 1and 2, the notches being spaced a distance proportionate to the rotarymotion imparted to the shaft 118 by the conversion mechanism.

The'rotary conversion mechanism on one side of the dual actuator isdesigned to actuate the shaft in one direction and the conversionmechanism on the opposite side of the dual actuator is designed torotate the shaft 118 in the opposite direction. Slippage permitted byeach clutch lining 72a when the associated bladder 112 Vis not underpressure permits the two rota-ry conversion mechanisms to operatesubstantially independently. Thus one of the conversion mechanisms maybe employed to repeatedly rotate the shaft 118 in a stepwise manner in agiven directio-n without interference from lthe other conversionmechanism.

Although the preferred embodiment of the device has been described, itwill be understood that within t-he purview of this invention variouschanges may be made in the form, details, proportion and arrangement ofparts, the combination thereof and mode of operation, which generallystated consist in a device capable of carrying out the objects setforth, as disclosed and defined in the appended claims.

The invention having been thus described, the following is claimed:

1. In a iluid powered actuator device for imparting movement to a shaft,said device including a housing provided with a generally cylindricalchamber, said shaft passing axially through said chamber, and expansiblemeans disposed in said chamber responsive to fluid under pressure fordelivering an axial thrust, the improvement wherein said expansiblemeans includes an elastomeric bladder having the shape substantially ofa toroidal ring and having a continuous open seam in its outer peripheryparallel to the plane thereof, said housing comprising two partsseparable along a juncture occupying a plane normal to the axis of saidcylindrical chamber, said bladder being disposedI in said chamber inencircling relation Vto' said shaft with its seam seated'in the junctureof said yseparable parts, means securing said parts in compressiveengagement along said juncture to close the seam in said bladder, andmeans providing a fluid conduit passing through the wall of said housinginto said bladder for delivery `of fluid under pressure thereto. f

2. In a iluid actuator device for imparting movement to a shaftselectively in opposite directions, said device including a pair ofhousing members each provided with `a cylindrical chamber and supportedwith their chambers 6 boring leading from each side thereof to theexterior of said device, a hollow pin press-fitted in each boring insaid base member, there being one said pin projecting from each side ofsaid base member and penetrating into the adjacent bladder, each saidpin having an annular flange projecting therefrom within the adjacentbladder compressing the wall of the bladder against the side of the basemember to effect a seal therewith.

3. In a lluid powered actuator device, a housing having a cylindricalcavity, a shaft journalled in said housing and passing axially throughsaid cavity, an expansible toroidal bladder encircling said shaftadjacent one end of said cavity, means for conveying fluid underpressure to said bladder, and means enclosing said bladder andcooperating therewith to form an expansible chamber, said meanscomprising a pair of plates positioned for sliding axial movement insaid cavity adjacent said bladder, and a sleeve surrounding said shaftand passing through said bladder, said plates having central aperturesthrough which said sleeve passes, one plate having a central aperturesnugly fitting said sleeve and having an outer pen'phery spaced from thecylindrical wall of said cavity, the other plate having a centralaperture spaced from the periphery of said sleeve and rhaving an outercircular periphery snugly tting the cylindrical Wall of said cavity.

4. In a iiuid powered actuator device; a toroidal bladder, and meansproviding an expansible chamber for said bladder comprising a housinghaving a cylindrical chamber, said housingsupporting a cylindricalmember extending coaxially into said chamber, said bladder beingdisposed in said 4chamber in surrounding relation to said cylindricalmember, and a pair of adjacent plate members journalled for axialmovement on said cylindrical member adjacent said bladder, said bladderbeing confined between said plate members and an end wall of saidhousing, one plate member having a central aperture snugly fitting saidcylindrical member and an outer periphery spaced from the inner wall-ofsaid cavity, the other plate member having a central aperture looselytting said cylindrical member and an outer periphery snugly fitting theinner wall of said cavity, the construci tion and arrangement being suchthat said plate members cooperate t-o coniine said toroidal bladderWhile remaining free to move axially within -said chamber toaccommod-ate expansion and contraction movements of said bladder.

References Cited in the tile of this patent Kendig L. Apr. 21, 1959

